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SN 2012aa: A transient between Type Ibc core-collapse and superluminous supernovae

Roy, R. and Sollerman, J. and Silverman, J. M. and Pastorello, A. and Fransson, C. and Drake, A. J. and Taddia, F. and Fremling, C. and Kankare, E. and Kumar, B. and Cappellaro, E. and Bose, S. and Benetti, S. and Filippenko, A. V. and Valenti, S. and Nyholm, A. and Ergon, M. and Sutaria, F. and Kumar, B. and Pandey, S. B. and Nicholl, M. and García-Álvarez, D. and Tomasella, L. and Karamehmetoglu, E. and Migotto, K. (2016) SN 2012aa: A transient between Type Ibc core-collapse and superluminous supernovae. Astronomy and Astrophysics, 596 . Art. No. A67. ISSN 0004-6361.

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Context. Research on supernovae (SNe) over the past decade has confirmed that there is a distinct class of events which are much more luminous (by ~2 mag) than canonical core-collapse SNe (CCSNe). These events with visual peak magnitudes ≲–21 are called superluminous SNe (SLSNe). The mechanism that powers the light curves of SLSNe is still not well understood. The proposed scenarios are circumstellar interaction, the emergence of a magnetar after core collapse, or disruption of a massive star through pair production. Aims. There are a few intermediate events which have luminosities between these two classes. They are important for constraining the nature of the progenitors of these two different populations and their environments and powering mechanisms. Here we study one such object, SN 2012aa. Methods. We observed and analysed the evolution of the luminous Type Ic SN 2012aa. The event was discovered by the Lick Observatory Supernova Search in an anonymous galaxy (z ≈ 0.08). The optical photometric and spectroscopic follow-up observations were conducted over a time span of about 120 days. Results. With an absolute V-band peak of ~− 20 mag, the SN is an intermediate-luminosity transient between regular SNe Ibc and SLSNe. SN 2012aa also exhibits an unusual secondary bump after the maximum in its light curve. For SN 2012aa, we interpret this as a manifestation of SN-shock interaction with the circumstellar medium (CSM). If we assume a ^(56)Ni-powered ejecta, the quasi-bolometric light curve requires roughly 1.3 M⊙ of ^(56)Ni and an ejected mass of ~14M⊙. This also implies a high kinetic energy of the explosion, ~5.4 × 10^(51) erg. On the other hand, the unusually broad light curve along with the secondary peak indicate the possibility of interaction with CSM. The third alternative is the presence of a central engine releasing spin energy that eventually powers the light curve over a long time. The host of SN 2012aa is a star-forming Sa/Sb/Sbc galaxy. Conclusions. Although the spectral properties of SN 2012aa and its velocity evolution are comparable to those of normal SNe Ibc, its broad light curve along with a large peak luminosity distinguish it from canonical CCSNe, suggesting that the event is an intermediate-luminosity transient between CCSNe and SLSNe at least in terms of peak luminosity. In comparison to other SNe, we argue that SN 2012aa belongs to a subclass where CSM interaction plays a significant role in powering the SN, at least during the initial stages of evolution.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Sollerman, J.0000-0003-1546-6615
Fremling, C.0000-0002-4223-103X
Filippenko, A. V.0000-0003-3460-0103
Additional Information:© 2016 ESO. Article published by EDP Sciences. Received: 11 December 2015; Accepted: 1 July 2016; Published online 01 December 2016. We thank all of the observers at ST who provided their valuable time and support for observations of SN 2012aa. We are grateful to the staff of the CT, IGO, TNG, NTT, Lick, and Keck-I telescopes for their kind cooperation when conducting the observations. This work is partially based on observations made with the NOT, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias; on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias; and on observations made with NTT Telescope at the La Silla and Paranal Observatories within the European supernova collaboration involved in ESO-NTT large programme 184.D-1140 led by Stefano Benetti. Some of the data presented here were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration (NASA); the observatory was made possible by the generous financial support of the W. M. Keck Foundation. We thank G. Leloudas for a valuable discussion of a draft of this paper. J.M.S. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1302771. A.P., E.C., S.B., and L.T. are partially supported by the PRIN-INAF 2014 under the project “Transient Universe: unveiling new types of stellar explosions with PESSTO”. A.V.F.’s research is supported by the Christopher R. Redlich Fund, the TABASGO Foundation, and NSF grant AST-1211916. Research at Lick Observatory is partially supported by a generous gift from Google. This work has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. We also used NASA’s Astrophysics Data System.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
NSF Astronomy and Astrophysics FellowshipAST-1302771
Istituto Nazionale di Astrofisica (INAF)UNSPECIFIED
Christopher R. Redlich FundUNSPECIFIED
Subject Keywords:supernovae: general / supernovae: individual: SN 2012aa
Record Number:CaltechAUTHORS:20170202-123746017
Persistent URL:
Official Citation:SN 2012aa: A transient between Type Ibc core-collapse and superluminous supernovae R. Roy, J. Sollerman, J. M. Silverman, A. Pastorello, C. Fransson, A. Drake, F. Taddia, C. Fremling, E. Kankare, B. Kumar, E. Cappellaro, S. Bose, S. Benetti, A. V. Filippenko, S. Valenti, A. Nyholm, M. Ergon, F. Sutaria, B. Kumar, S. B. Pandey, M. Nicholl, D. Garcia-Álvarez, L. Tomasella, E. Karamehmetoglu and K. Migotto A&A, 596 (2016) A67 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:73989
Deposited By: Tony Diaz
Deposited On:02 Feb 2017 21:02
Last Modified:03 Oct 2019 16:33

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